Impact hammer



Oct.` 13, 1942. J, M scHMlED 2,298,845

y IMPACT HAMMER Filed July 30, 1941 2 Sheets-Sheet 2 l INVENT OR.

Patented Oct. 13; 1942 2,298,845'Trl D? PAI ENT O'F FIGEZ IIVIPACTHAlWlWER-f Application J uly, 30,- 1941,..S,erial.Not .404,633l

(C11 M5L-33) 10` Claims.v

The present inventionerelates fto improvementsin'` impact hammers.hand;` more` particularly; to power driven impact hammers havingr;readily controllable4 speed? and'; concussion :variables:V

Heretofore f attempts f have been made to fvary the force. ofafblowtgiven Vbyearrimpact hammer and.n toA vary# the :speed with whichsuccessive creasing the air;- supply: However;',withithe-morepovrverfu'l` ablowy` the: speed of successive fblows isincreased `whilefin light impact-worm the :speed of successive blows isgreatly-,f decreased; This mean's a'- greatdossf ortimerinrfragilelongfwork performance, while. thef increased l number@`of blowsin heavy` work'.` causesvunduef wear.v to -the tool:` andlaborfto- .theroperatorfin :handling-dt:`

Most impact hammers lfailfbecause shocks land vibrations from therepeated impacts areftra-ns-Y mitted tof the motor.` windings*V gears-Aand fantifriction bearings; This-likewise tires='thefopera tor; andhasbecomeronefof the.u problems inthis type-of implement. Afurtherfproblem in thesetools has-beenf-gettinggridof the Vfrictionasl`heat generated' byf the? rapidlymoving; partsthat' isv otherwiseYdestructive to?" the mechanism:

Onerobj ectflof the --fpresentfinvention iis-fito provide asimplefandeffective -meansf'of -lvarying the impact rblow from one that` 'is`ha-rcL and fslowl to one that isfastandlighta l Another .objectisvtoprovide :an .impact hammer. havinga. simple. and leiective compressionmovement'that is.easily regulable from heavy talight work. .l s t Afurther Objectis to provide an impact .hamm'er having'improved"shockabsorbing means'v for the. protection of "the'parts and-of' theoperator.

A still"furtherpbject is to provide -Van impact hammerwitli animprovedcoolingrsystem that will tend to maintain rthehammer in a relativelycool condition and prevent overheating.l

A yet further objectis to provide an impact hammer that is easilyandreadily assembled' and disassembled, that'v may be.` adjusted withoutsacrice of speedv tovarious kinds oiwork,` that is'` less." wearingfonthe' parts and operator, .and Will not.overheat.`

In the accompanying drawingsf one@ embodi- CII ment of theinventionisvshow-rr and isgdescribed 55` in the. following.specification.. for purposes.J of exemplii'lcation lonly... Various..other modifications and adaptations will at oncefbecome rap.-u parent toone skilled, in .the art.-

Inv thedrawings.

ZET-ig.` 1. is arview, .partlyfinsection,. througha hammer embodying-`the present-invention; j

Fig. 2.v isa vview'takerron.the line. 2-2..of-. Fig.. 1;- partly; invsection, lookinglin 4'the directiomof the arrows;

Eig. 3 :is -a .view taken lon Lthe.4 line, 3.7-3. ofiFig l, partly insection, looking inthe..directiomof the 'arrows Figffl-is aview-partly-in ysection of a regulating collarand-bearing usable withthe invention;

Fig. 5 is av sectional `viewrthroughy `the' :collar oi Fig'. 4i

Fig..r 6 isafplan view-ofthe hammer-withithe. housingfpartial-1yremoved;` showingr the opera-` tion of the compressionmechanism diagram-,- matically; and:

ligf4 7 `is ,-a.-view diagrammatically.showing ,certainvo-fr vtheparts`of- 'Figi 6- in elevation.

Infaccomplishingthe objects of this invention the-body1 portionorhousing-oi theham-mer is made Vup of simple'easily assembledparts..Briefly, reciprocable. impar-:tl ham-mer member. is operated by aspringmeans-thatis lcompressed. slowly at low `spring'lpressure by a `motordriven actuatingmeans `that provides an` increase in speedV ofcompressionrtoward a maximum and then a lessening-ofrthespeedruntil themaximum compression'is attained', when` the springlisreleasedto-'drivefY the' impact .memberv forward. A regulating or adjustingmeans isusedto vary the compression offthefspring means prior to` itsrelease for'action `on the hammer in-givingfan operative-blow. As o. thespring compressionmis. varied, a heavier orl lighter loadeis laddedtoethe motor which increases or f decreases -the speed' oi consecutive'blows accordingly;

Shock? absorbing means `is-"mounted` adjacent the tool holding' portionoi 'the hammer 'tolessen the vibration and f reactional 'shocks'transmitted to the housing and hammer `as a whole, and'thus to the body'of the operator. Other sh'oclabsorbing means is mounted in the impactmember operatingassembly to absorb shocks and vibrationsbetween pinionandgear members, the anti-'- frictionr bearings, motor windings, andother parts..

The rapidly moving impact member is used as appart`of.thecooling=,system.to suck in outside airto;flush ,thegears bearingsand-.,entirehousing and to force out heated air in combination with anovel valve and groove arrangement.

As shown, the impact hammer mechanism is mounted in a housing comprisinga barrel portion I6, a gear housing II and a motor housing I2 allproperly united into a ruggedly built and easily assembled whole throughthe use of bolts or other means not shown.

The barrel portion I includes a cylindrical bore I4 having a restrictedbearing portion I1 in which an impact or hammer member I3 isreciprocally mounted. At the forward end of the impact member is anenlarged head member I5 having a tool driving face portion I6 and ashouldered portion I8 forming a bearing for one end of a hammeractuating spring means in the form of a compression spring member thatis coiled around the stem 22 of the impact member.

The enlarged head member I5 slidably ts the bearing portion I1 of thebore I4 in the manner of a piston and reciprocates along the surface ofthe bearing, serving to position and guide the impact member at thatplace.

Adjacent its rear, the stem 22 of the impact member extends through anannular collar 24 and is sildably mounted therein. This collar isadjustably secured to the bore I4 of the barrel and forms a rear bearingfor the impact member and properly positions and guides it at thatpoint. This adjustable collar at its forward end forms astop or bearing25 for the other end of the spring member 20.

The collar 24 is slightly spaced from the stem 22 of the impact memberto form a. stand-off thrust bearing and to afford a relatively loose fitbetween the stem and bearing at this point. This prevents any seizing orbinding caused by the expansion of the parts from the heat created underthe normal frictional engagement of the parts.

The collar 24 is adjustable axially of the stem 22 in the bore I4 tovary the compression of the spring 20 and thus to Vary the force of theblow to be given by the hammer member I3. On the collar 24 a helicalthread 26 is formed terminating in a iiat top portion having screwthreads 23 cut therein for purposes to be described hereinafter. At itsrear portion, the bore I4 is screw threaded to form a nut portion toengage screw threads 28 on the helix of the compression collar 24. Aturning Vof the adjusting collar member in the nut portion 30 causes thecollar to travel along the screw threaded portion of the bore tocompress or release pressure on the spring member 20 and thereby adjustthe force of the blow to be given by the impact member.

To obtain this turning movement for regulating and adjusting the springpressure, an adjusting worm screw 21 may be used. As shown, screw orbolt 21 extends into housing I I and has flights 3! arranged therearoundto intermesh with helix 26 through a groove 32 in the barrel I0. Aknurled cap on one end of the screw 21 and exterior to the housing maybe used to obtain the desired tension on the spring.

A cylindrical bore 34 in the housing II accommodates the screw 21. Thisscrew may be hollow or formed with a cylindrical housingto receive asmall compression spring 35 resting against its inner end and extendingoutwardly beyond the F same into contact with the inner end of bore 34.This spring tends to urge the bolt 21 out of the bore 34.

To counteract this pressure, the screw is annularly grooved as at 36(Fig. 3) and a pin 31 ex- 75 tends through an opening in the housing IIand rides in the groove to hold the bolt in place. In the periphery ofthe groove 36 a wider locking notch portion 38 is formed to cause thebolt to lock against turning by contact with pin 36 through pressurefrom spring 35. Other widened lockingportions 38 may be inserted aroundthe periphery of the screw 21, if desired. For further adjustment afterthe pin has locked in the portion 38, the bolt must be pressed inwardlyagainst the pressure of spring 35, and it may then be turned easily asthe pin 31 now rides in the main portion of annular groove 36. By thisarrangement the bolt 21 is held in a predetermined adjusted positionfrom which it cannot be dislodged by the vibration of the impact hammer.Only by manually adjusting the bolt can the compression of spring 20 bechanged. If in adjusting the spring pressure, the operator does not lockthe bolt in the nearest locking groove, vibration of the hammer membermay loosen the bolt 21 only to a point where it will lock itself in theadjacent notch 38.

The return means for the hammer after an operative action by the springmeans is simple and works smoothly and with less shock to the motor andgear members than that customarily in use. At its inner end the stem 22is reduced in size and bent downwardly to form a hook-like projectingmember 40. The upper portion of this projecting member is flattened at42 to pass under, and to be received within guide ilanges 43 of a rollerbearing guide member 44 (Figs. l and 2) properly mounted in the housingI I. The purpose of this guide means is to position the impact member I3with respect to the bore I4 and the operating mechanism to be describedand to prevent the hammer member from turning or rotating in the barrel.

Within the motor housing I 2 is a standard universal motor 46. A motordriven shaft 48 extends upwardly from the motor 46 into the gear housingII and carries a pinion 50 adjacent its upper end to mesh with teeth 52on a gear assembly 54.

The gear assembly is formed to absorb shocks resulting from thevibration of the hammer, thereby preventing injury to the more delicateparts of the mechanism. It consists of several parts including an outerring-like member provided with gear teeth 52 and an inner hub member 56mounted onaspindle 51in a ball bearing mounting. Between the ring-likemember and the hub, and spacing them from one another, is an annularshock absorbing ring 58 of rubber, or other similar resilient material,inserted between the two with a press fit. The shock absorbing ring maybe enclosed on either side by the two metal annular members 59 and 60.This shock absorbing means also acts to overcome inertia in theactuating mechanism and provides an easier starting action to the motorin overcoming the force of spring 20 at each operating contact of themechanism with the hammer member I3.

For compactness of assembly the barrel I0 may extend rearwardly overpinion 50 and a portion of the gear assembly 54 that may be formed asshown for this purpose.

Mounted eccentrically on the hub 56 is a spindle 6I that carries aroller hammer actuating member 62 mounted thereon. This member 62, uponrotation of the gear assembly, acts on the downwardly hooked portion 64of the projecting member 46 to urge the hammer I3 rearaanmaninwararagain-.sti megas-noaa @funespringtmeml Frein tne-difagrammfatioviews-sonnige. oand-.t 1?

ber-1 6121'intermittentlyf'strikstheiiinner fak-ieV 66? off thehookllikef member: adjacentione edge byl'tle -arrew-'B"-. Thisl-meansthatati thei'point ofE contactl the rollerfmember strikes the face'- 66at ant exceedingly?aoutefangl andbegins Theispeed of compression .is-`greatly ir'rcreasedvv through' any arc-f ofsubstantially 909i andf'then, duringftliefperiod off greatestcompression; the speed gradually-1decreases 2 toV I the1 point of i departure or disengagement with facef65.

thefpoint ofiw departure andi at the maxir'num` sion yof spring';

Were the gearassembly" centered wth the e.Xis'`of` the hammer member;the face-portion 65 would-have to `beL shortened orth`ere"would` be alonger contact of the roller 62`-with""theY projecting memberat thepoint approximating maximum spring compression with consequent greaterstrain on the parts. The roller E2 would disengage from the face 66after the point of maximum spring compression had been reached. Theguide member 44 in cooperation with the attened portion 42 providesmeans for maintaining the projecting member and its hooklike member 64in proper or operative position to be actuated by the crank roller B2.

It will be apparent that as the screw 21 is adjusted, compression of thespring 20 will be increased or decreased. This will have a directrelation on the motor assembly 46. By increasing the spring tension, themotor will be slowed under the heavier work given to it and the resultwill be a slower, harder blow by the hammer I0. By decreasing the springtension the load on the motor will be lessened, permitting a rapidrotation and a resulting light, fast blow.

At the rear end of the hammer assembly, the gear housing Il is formedwith a handle portion 10 and a trigger switch arrangement 12 by which aproper electrical connection to the mo- At-v its l forward? end`the-barrel Ii'lis i provided with a toollholdiig1v device and-lafur-ther-lsliockf absorbing strueture: A't its mouth thefbarrel lii'ssliglfitlyconstrictedl` In' this constricted' portion a groovedtool-holding member "is in serted", -and is separatedfrom the barrelfmember by a rubber' annulus "T6, or shock absorbing means, somewhatsimilar in*-` structureL to the shockabsorbing memberlf Again;a.-p1ess`-i"1't` may be used for assembling these members.A

All tool-I havingf ak istem portion 18'?- may' be in-A serted in thetoolhholdingmember' and? friction-- ally heldth'erein; A'ileath'ergasketlor cushion 8l! 'may li'e against' the inner sidei offftli'e constricted portion-"of tlien'ioutli to receiiA/eI the eX cess blow" fromlthe' headV l'of the hammer if"A no tool sh'ank' is inthe tolilioldingfmember; Pressure of,l the; tool on the workwill slidablyreturn-the `tooland`` its stem? 18?' into auf 0perativen position to receive a blow@from theu ham# mer Il);l Directfvibrationfromthe tool-will be absorbedbyv resilientl means 16 tending tolpre- Vent shocks from being'transmitted to the barrel and lto the-Ioperators 'lands:'

The tolU4 holding member mayv beinternally spirally-` grooved as-*at i8-2 i to forml a tortu'ous`- air passage for permittingfiigressofcool-Iou'ter air v upon a=-b"a'ckwardl air"sucling-fmovementiof thehammer headl I 5 andv'egress to h'eatedi airrup'on` a forwardair pushingmovement'of``this pistonlike member. This "interchange of air tends'tomair'rtain*` thefparts of the`-hammer at ,itsforf Ward-'en'din arelativelyacool condition 'andpre- Vents over-heating.r

Fr-fcoolig the-gears; andmotor housing; theA mechanisms therein, and:the vcyli"nd1`-ical bore; an ai inleti vailveshown as' aA`ball"`se'aled"` oiler4 84'mayf beltinsertediin' the housing`- Hi Uponanoperative forwardstrokefof the hammer I3, outside` air WililVbedrawninto the housing" Il andpass arounditheivariousparts and intothe' borepastfthecollar' 24: Anotherball 'sealed oiler 86* acting' asb arr airoutlet Valve may be mountedin reverselin' thehousing H toY permit heatedairi to be-expelled from the'housin'g by the' reverse^stroke of' thehammer IB caused by thejroller' 64? Oiler 84 may also" be used forlubricatingr the moving parts.`

Both the head !5""and"the"`stem"20are'pror vided lwitli lubricatinggrooves 88to -carry"`lubricating material in the bore I4 to theirrespective bearings.

The invention herein described may be incorporated into `various otherembodiments and modifications that will be apparent to those skilled inthe art. All such embodiments coming within the spirit of the inventionare intended to be included within the scope of the appended claims.

I claim:

1. An impact hammer, including a reciprocable hammer member, a barrelhousing enclosing said hammer member and having a mouth portion, a toolholding member in said mouth portion, said tool holding member beingseparated from said mouth portion by a shock absorbing member.

2. An impact hammer, including a housing, a piston-like hammer memberreciprocably mounted Within said housing, an air inlet Valve in saidhousing operable to admit air on movement of said member in onedirection and an air outlet valve in said housing to permit egress ofair from the housing on movement of said member in the other direction.

3. An impact hammer as defined in claim 2, wherein the air inlet andoutlet valves are ball sealed oiler members and the outlet valve ismounted to be operative from the interior only of said housing.

4. In an impact hammer having a housing and a reciprocable hammer memberslidably mounted in said housing, means for varying the force of theblow to be given by said hammer member, said means including acompression spring operatively mounted at one end to said hammer member,a screw threaded portion in said housing adjacent the other end of saidspring member, a threaded adjusting member for said spring mounted insaid housing with its threads in operative engagement with the threadedportion of said housing and forming a stop member for the last mentionedend of said spring member, a helix on said adjusting member, and manualadjusting means meshing with said helix to turn said adjusting memberalong the screw threaded portion in said housing to compress or releasetension on said spring member.

5. An impact hammer as defined in claim 4, wherein said adjusting memberis formed as a collar around said hammer member and has a slidingengagement therewith.

6. An impact hammer, including a barrel housing having a mouth portion,a piston-like hammer member reciprocably mounted within said housing, atool holding member in said mouth portion, and Ventilating groovestortuously formed in said tool holding member operable to permittortuous ingress of air to said housing 0n movement of said hammermember in one direction and tortuous egress of air on movement of saidhammer member in the other direction.

7. An impact hammer, including a barrel housing having a mouth portion,a piston-like hammer member reciprocably mounted within said housing, atool holding member in said mouth portion, and Ventilating groovesformed in said tool holding member operable to permit ingress of air tosaid housing on movement of said hammer member in one direction andegress of air on movement of said hammer member in the other direction,said grooves being formed spirally around the interior of said toolholding member adjacent any tool held therein.

8. An impact hammer member, including a housing, a hammer memberreciprocably mounted in said housing, spring means for reciprocatingsaid hammer for an operative blow in one direction, and return means forreciprocating said hammer in the other direction against the action ofsaid spring means, said return means including a motor operated shafthaving a pinion thereon, a rotatable gear wheel meshing with saidpinion, a crank member eccentrically mounted on said gear wheel, and aprojecting member on said hammer member for intermittent operativeengagement by said crank member as it rotates in the orbit of said gearwheel, the radius of engagement of said crank member with said hooklikemember from the center of said gear Wheel increasing from the point ofcontact to the point of departure from said projecting member.

9. An impact hammer member, including a housing, a hammer memberreciprocably mounted in said housing, spring means for reciprocatingsaid hammer for an operative blow in one direction, and return means forreciprocating said hammer in the other direction against the action ofsaid spring means, said return means including a motor operated shafthaving a pinion thereon, a rotatable gear Wheel meshing with saidpinion, a crank member eccentrically mounted on said gear wheel, and aprojecting member on said hammer member for intermittent operativeengagement by said crank member as it rotates in the orbit of said gearwheel, said gear wheel being so mounted that a diameter therethroughWill pass substantially through the point of engagement anddisengagement of said crank member with said projecting member.

10. An impact hammer, including a housing, a hammer member reciprocablymounted in said housing ,means for reciprocating said hammer member foran operative blow in one direction, member in another direction toposition the same return means for reciprocating said hammer for anoperative blow, and guide means in said housing cooperating with saidhammer member to maintain said hammer member in operative position to beactuated by said return means, said guide means including a flattenedportion on said hammer member and a roller guide member mounted in saidhousing contacting said iiattened portion to prevent rotation of saidhammer in the housing.

JOSEPH M. SCHMIED.

CERTIFICATE oF CORRECTION. Patent No. 2,298,8LT5. october 15, 19h@JOSEPH M. SCHMIED.

It .is hereb)T Certified that error, appears in the 'printedspecification of the above numbered patent requiring correction asfollows; Page 2, first Column, line 26, for '"Sldably" read--slidably--g page )4., second oo'imnn,4 Y

` line [4.0, e' La L1:n2LO,strikev out member in another direction toposition the same and insert the same after "hammer" in linelil, sameclaim; and that the said Letters Patent should be read with thisveorreetion therein that the same may c'onfonn to the record of the Casein the Patent Office.

Signed and sealed this 214th day of November, A. D. 19lL2.

. Henry Van Azfsdale,v (Seal) 4 Acting Commissioner of Patents.

